The allowed clearance is a minimum of 750mm above the burners and a minumun of 50mm of side clearance from the burner. Unless manufacturers instructions state otherwise.
[automerge]1579084393[/automerge]
It is measured from the burners, not from the actual edge of the hob spill over tray. all the hobs I see & have installed already make the allowance of a min 50mm side clearance from the burner to the edge of the spillover tray so you only need the wall unit directly above the hob to have a min of 750mm clearance above it. If your hob is 595mm wide as most 4 burners are; then a standard 600mm bridging unit above it will satisfy the regs and give you the min 50mm side clearance needed. Hope that clears things up for you & explains why it passes the CP12.
[automerge]1579084899[/automerge]
I have never seen a gas hob mi's to state a clearance of less than 750mm, an electric hob yes but not gas.